Yes, they are a big part of the problem BUT NOT the whole problem.

One can get a clear view of this when they are welcomed to your country, town or villa, with all the goodies included for a comfortable life:

one good house
one good job

A couple weeks go by and they don't show up at work, they start bringing their relatives, friends and whatnot, their house starts getting parties and fights everyday and every night, small robbery starts in your zone, etc etc etc.

In 6 months you have a small guetto around you and crime like you never thought it was possible in that zone.

Then you start to get called "racist!" cause you want to go on YOUR peaceful and secure life.

So yeah, they're not the whole problem - just 99% of it.